Deposition effect of carbon deposits on charge flow in EGR valve equipped CI engine

Abstract

The exhaust gas recirculation (EGR) valve regulates the exhaust gas flow between the engine exhaust manifold and the inlet one. This allows the inlet air to warm up, improving fuel evaporation and reducing the combustion temperature of the charge. Such a valve reduces the number of harmful substances in the exhaust gases. The valve tends to stick when too much sediment builds on the walls of the exhaust system, especially during driving in urban conditions or when leaks in the vacuum or exhaust pipes occur. A faulty valve causes the engine to run unevenly at idle speed and under light loads. The defective EGR valve weakens the inlet manifold capacity, increases combustion, causes clogging of the particulate filter and damage to the lambda probe. Blocked EGR valve may lead to engine immobilization as a result of its computerized control system operations. A model of an EGR valve for a selected diesel engine was developed to determine velocity distribution of the load flowing in it for different values of the degree of valve opening and the volume of deposits on the valve walls. The volume of accumulated carbon deposits on the walls of the EGR valve was measured using a real engine. Based on the recorded mileage of the vehicle, the assumed average speed of the car and the driving style of the driver and the intensity of deposition of carbon particles on the walls was estimated.